Long-term thinking is one of the most important success drivers for investors. Companies with strong and sustainable competitive advantages add value over the years regardless of external conditions; investing in these kinds of businesses puts time on your side. Costco (NASDAQ:COST), Coca-Cola (NYSE:KO), and Disney (NYSE:DIS) are three great candidates to buy and hold forever.

Costco is built to last
People want to buy all kinds of products for conveniently low prices; that's not going to change with trends or the economic cycle. Costco provides a high-quality shopping experience and unbeatable prices, and the company is strong enough to stand the test of time.

Costco's smart and efficient business model is an amazing source of sustainable competitive strength. The company makes most of its profits from membership fees as opposed to gains on merchandise sales, which allows Costco to sell its products at cost and deliver remarkably low prices to customers.

This business model resonates remarkably well among clients: Renewal rates have consistently been above the 85% level through the last several years, and the last quarter was as strong as ever, with global renewal rates near 87% and big markets like the U.S. and Canada seeing renewal rates above 90%.

Costco continues to expand its store base; the company is planning to open a total of 30 new units in fiscal 2014, a nearly 5% increase in square footage for fiscal 2014 versus fiscal 2013. Costco is giving more relevance to international locations lately -- and considering that the company is still taking its first steps when it comes to global expansion, international markets could be a big growth driver for Costco in the coming years.

Always Coca-Cola
Coca-Cola is the undisputed global leader in the soft drinks market. The company owns 16 brands that generating more than $1 billion in annual revenues, including names like 
Diet Coke, Fanta, Sprite, Coca-Cola Zero, Dasani, Powerade, and Minute Maid, among many others. An unparalleled distribution network, abundant financial resources, and deep global reach provide formidable competitive strengths for the company.

Coke is facing stagnant volume growth in developed markets because of market saturation and the trend toward healthier nutrition. But the company is focusing on alternatives like sports drinks and waters to adapt to changing consumer habits in those countries, while emerging markets are still offering plenty of room for volume growth in both traditional carbonated drinks and healthier choices.

Coca-Cola is part of the Dividend Aristocrats Index, a select group of companies that has been able to increase dividends over the last 25 consecutive years. Even better, Coke makes most of its Dividend Aristocrat peers look like simple plebeians with its amazing track record of 51 consecutive dividend increases in a row.

Disney for investors of all ages
Disney benefits from its tremendously valuable intellectual property, which sets it apart from the competition. The company owns brands like ABC, ESPN, and Pixar, among others, and it has the rights to profit from an amazing portfolio of fictional characters, from Mickey Mouse to Darth Vader, including many of the most popular and recognizable names in the industry.

Disney has the ability to monetize its characters and franchises across multiple platforms: movies, shows, home videos, theme parks, merchandising, video games, etc. This provides a lot of leverage when it comes to making money from its properties, and it's an unparalleled advantage in the media and entertainment industry.

Discretionary spending and advertising tend to fluctuate considerably with the business cycle, so the company isn't immune to economic volatility. But Disney has proven its ability to successfully go through the ups and downs of the economic cycle while at the same time creating value for shareholders over the years.

Disney is an intergenerational company that's built a long-lasting emotional bond with parents and kids of different ages all over the world. Considering its unique portfolio of brands and intellectual properties, in addition to a management team that knows how to create value from those assets, the company has what it takes to continue thriving for years to come.

Bottom line
A long-term strategic approach to investing is one of the biggest advantages investors can have over the typically shortsighted mentality that reigns in Wall Street. Costco, Coca-Cola, and Disney are three well-run companies benefiting from rock-solid competitive strengths; this makes them attractive candidates for investors looking for businesses of strong enough quality to hold forever.

This article represents the opinion of the writer, who may disagree with the “official” recommendation position of a Motley Fool premium advisory service. We’re motley! Questioning an investing thesis -- even one of our own -- helps us all think critically about investing and make decisions that help us become smarter, happier, and richer.